Plants activate defense signaling pathway depending on the feeding guild of the attacking herbivores. Usually two signaling pathways namely, Salicylic acid (SA), Jasmonic acid (JA), mediate plant responses to insect attacks. When attacked by multiple herbivores, the two signaling interact in ways whose outcome may be complicated. To investigate this cross talk phenomenon we infested wild type and SA insufficient mutant plant types of Arabidopsis thaliana L. with only Pluetella xylostella L. caterpillars, only adult Brevicoryne brassicae L. aphids and with both caterpillars and aphids. We analyzed the insect performances and the underlying defense mechanisms in the plant via expression levels of the marker genes for JA (LOX2) and SA (PR1). The caterpillar accumulated higher biomass in dual infested wild type and SA treated wild type plants in comparison to the rest of the treatments. The higher biomass of caterpillar in these treatments was attributed to suppression of plants’ JA mediated defense systems by SA. The SA antagonism of JA mediated defense system was supported by lower expression levels of LOX2. In dual infestations, aphids performed better under SA insufficient mutants compared to wild type plants pointing to possible activation of SA mediated defense in the wild type plants in response to attacks by aphids. Our results show that the phloem feeder weakened JA-related plant defenses, thus facilitating the growth and development of the leaf chewers. We conclude that such facilitative inter-guild interactions may present serious challenges to beneficially harnessing the natural plant defense systems against herbivory.